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We present new dynamical mass estimates for a sample of brown dwarf binaries with sufficient precision (

Organelle DNA from 11 populations of the marine red alga Gracilaria verrucosa (Hudson) Papenfuss or similar species, and one population of G. sordida W. Nelson as an outlier, was digested with five restriction endonucleases. Visual inspection, parsimonious tree construction and UPGMA cluster analyses of the resultant banding patterns revealed a G. verrucosa core group composed of strains from Wales, Norway, France, Argentina and Japan, with closely similar if not always identical profiles. A second well-defined group, containing two strains from England and a second one from France, was determined to belong to the related genus Gracilariopsis. Two populations, from Brazil and North Carolina, USA, consistently formed a third group in numerical analyses, but visual differences in their profiles and the UPGMA distances between them were sufficient to indicate that they represented different species. Finally, a population from British Columbia, Canada, confirmed a posteriori as being G. pacifica Abbo...

The 18S rRNA gene from three scallop species (Placopecten magellanicus, Chlamys islandica, Argopecten irradians) and 7 mactrid clam species (Spisula solida, S. subtruncata, S. solidissima, Mactromeris polynyma, Tresus nuttallii, T. capax, Mulinia lateralis) have been fully sequenced. Phylogenetic analyses have supported the scheme of Waller (1991) for the Pectinidae but conflict with current evolutionary concepts and classification within the Mactridae. The Mactridae are shown to have evolved monophyletically. The current subfamilial position of Mactromeris, and the subgenera Spisula and Hemimactra of the genus Spisula, are not supported by this data.

Malignant hyperthermia is a rare syndrome that occurs in genetically susceptible individuals who are exposed to frequently used inhalation anesthetics. The disorder is most common in children and young adults. It is triggered through a defect in the ability of skeletal muscles to concentrate and release calcium. Signs of malignant hyperthermia include hypercarbia, muscle rigidity and tachycardia. Temperature elevation is often a late sign of the syndrome. Treatment begins with stopping all inhaled anesthetics at the earliest sign of the syndrome. The use of dantrolene has significantly reduced mortality from malignant hyperthermia. No simple screening test exists. Family members or those with a suspicious history need to be counseled and should consider muscle biopsy and testing prior to surgery.

Molisch (1937) coined the term allelopathy to refer to inhibitory or stimulatory biochemical interactions between plants, including the microorganisms traditionally placed in the plant kingdom. Thus, allelopathy could conceivably affect all phases of the nitrogen cycle which involve plants and microorganisms. This obviously includes most phases of the cycle.

Recognition of species in the Gracilariaceae, often notoriously difficult, is being aided by a combination of classical and modern techniques. We review some recent findings and present new results that may lead to redefinition of Gracilaria verrucosa, the type species of its genus. Plastid DNA restriction profiles (patterns of banding obtained by electrophoresis of DNA after restriction endonuclease digestion) from eleven strains ascribed to G. verrucosa indicated that the concept of this species in northern Europe includes possibly three taxa, one of which is known now to be a species of Gracilariopsis. In contrast, restriction profiles from Argentinian and Japanese strains were closely similar to the predominant pattern for European G. verrucosa. Profiles of several other strains, from the western Atlantic and eastern Pacific, were dissimilar to the European group and to each other. A chromosome number of n = 24 was determined for a representative of the predominant European group, and preliminary results of hybridization trials suggest that these strains, and others with approximately the same plastid DNA restriction pattern, are interfertile.

A new and improved method for the extraction and electrophoresis of enzymes and proteins of brown algal species has been developed. This method gives a more expedient sample preparation, a significantly enhanced enzyme yield and improved electrophoretic resolution over earlier methods. Twenty-one enzymes were examined spectrophotometrically and/or electrophoretically on polyacrylamide slab gels. Comparison of electrophoretograms were made between six species of the Order Fucales. The viability of this method in detecting inter- and intraspecific differences is demonstrated. The glycoprotein nature of some of the enzymes is explored and the effect on the electrophoretic mobility of the enzymes after treatment of the extract with exoglycosidases is demonstrated.

Productivities of two cohorts of Chordaria flagelliformis (O. F. Mull.) C. Ag. were estimated from measured changes in biomass and survivorship over time. Maximum productivity during the summer growing season was 2.6 g C m-2 d-1. Although this figure is relatively high, the short growing season results in an annual production of only 89 g C m-2. The significance of primary production by C. flagelliformis lies in its seasonal timing. During the summer growth period, 50% of production was recycled directly by detrital material. During the same time period, productivity and biomass losses of other seaweeds are at their lowest.

The genus Fucus L. is widely distributed through the cool temperate waters of the north Atlantic and north Pacific oceans. The very large number of sub-generic taxa (> 100) previously recognized was reduced by Powell (1963) to only 6 species. In his revision, Powell recognized F. distichus L. emend. Powell as the most variable of these. He classified the intra-specific variation in this species into 4 sub-species: F. distichus distichus, F. distichus anceps (Harv. et Ward ex. Carruthers) Powell, F. distichus evanescens (C.Ag) Powell and F. distichus edentatus (Pyl.) Powell. Because of reports that intermediate forms existed in Iceland (Jonsson, 1903) and the Faeröes (Börgesen, 1902), Powell (1957 a,b) decided to use sub-specific status rather than specific designation for these 4 taxa. However, within North America the 4 sub-species of F. distichus were often assigned specific rank (e.g. Taylor, 1957).

This investigation was concerned with toxicity and bioconcentration of zinc and cobalt in three species of algae as reflected by growth inhibition, algal accumulation of metal, and percentage uptake. Although there was generally an overall growth decrease from lower to higher metal concentrations (with the exception of the 2x zinc concentration), increased uptake and concentration of metals occurred in all three algal species. Therefore, the lower cellular weights resulting from high metal concentrations were more effective in accumulating zinc and cobalt. Chlorella vulgaris had a higher percentage uptake of zinc but a lower percentage uptake of cobalt than did Euglena viridis and Pediastrum tetras. Chlorella vulgaris thrived in surprisingly high concentrations of zinc. Euglena viridis concentrated the greatest amount of zinc, while both P. tetras and E. viridis had a higher affinity for cobalt than did C. vulgaris. Concentration of metal to an extreme degree was evident in all species studied. The three ...

The ratio of nitrate/ammonium in the soil decreases from a high level in the early stages of old field succession to a low level in the climax in the tall grass prairie region of central Oklahoma. Characteristic plant species from different stages of succession were grown in culture solutions where the total nitrogen content was held constant, but the form varied from nitrate only to ammonium only. The nitrate reductase activity of leaves and roots was measured in vivo. The results indicates that four pioneer species had relatively high levels of enzyme activity while four climax species had relatively low levels. Nitrate reductase activity was consistently higher in either the leaves or the roots of a species than in the other organ regardless of the nitrogen treatment. Enzyme activity generally decreased with decreasing nitrate concentrations, but seven cases were found where there were no significant differences in enzyme activity between any of the nitrogen treatments. All eight species had their highest shoot dry weights on the ammonium only treatment.

Helianthus annuus, an important species in the first stage of succession in infertile old-fields in Oklahoma and Kansas, was previously found to produce chlorogenic acid and scopolin which are inhibitory to many plants of the same successional stage. Consequently, investigations were made to determine effects of age and fertility on concentrations of those phenolics and related compounds in H. annuus. Concentrations of chlorogenic acid in control leaves of Helianthus annuus increased with age of the plant, and also in stems up to the 4th week of experimentation. Scopolin concentrations increased with age in old leaves and remained stable in the stems during most of the experimental treatment. Scopolin was not present in measurable amounts in young leaves or in roots. Chlorogenic acid concentrations were generally significantly higher in stems and leaves of mineral-deficient plants than in controls. Except for nitrogen-deficient plants, young leaves accumulated greater concentrations of chlorogenic acids than old leaves. Concentrations in roots were variable and no definite trends occurred. Band-510 (4-0-caffeoylquinic acid) and neochlorogenic acid were present in all plant tissues but not at all sampling times. Concentrations of both were generally higher in potassium-deficient stems, nitrogendeficient old leaves and stems, and sulfur-deficient old leaves, young leaves and stems than in controls. In addition neochlorogenic acid was generally higher in potassium-deficient young leaves than in controls. Band-510 was usually lower in concentration in nitrogen-deficient young leaves and roots, and neochlorogenic acid was generally lower in potassium-deficient roots than in controls. The concentrations of scopolin increased considerably, compared to the amounts in controls, in potassium-deficient old leaves, young leaves and stems during the last 3 weeks of treatment. In sulfur-deficient stems the scopolin concentration decreased with age but was generally not significantly different from the concentration in controls. Nitrogen deficiency decreased the concentration of scopolin in stems but had no other effects. The increased concentration of chlorogenic acids in sunflower with increase in age of plants and with mineral deficiencies probably increases the allelopathic effects of that species in the first stage of succession in infertile old-fields.